A known bookbinding system includes a signature conveyor assembly having a plurality of clamps which grip groups of signatures. The clamps carry the groups of signatures to a first station where a rotary knife cuts off the folds at the backs of the signatures. The books are then sequentially conveyed to a second station where the backs of the books are roughened. At one or more gluing stations, glue is applied to the roughened backs of the books. A cover feeder is effective to sequentially feed open covers to a covering station in a registered relationship with the books. After the covers have been applied to the books, the covers are formed by a cover breaker. The books are then delivered to trimmers for suitable trimming operations.
If the cover feeder in a known bindery fails to feed a cover to a covering station, the bindery is stopped and the malfunction of the cover feeding apparatus is corrected. If double covers are fed to the covering station, a jam-up or other malfunction of the covering apparatus may occur. Whether the covering apparatus fails to feed a cover or feeds double covers, it is necessary to stop the bindery and interrupt production in order to correct the fault.